Device for producing electrical signals by means of a control stick

ABSTRACT

A device for producing electrical signals, comprises a control stick which is pivotally mounted for back and forward movement intermediate its length. One end of the control stick, for example the bottom end, is provided with a source of luminous radiation adjacent this end, and the stick is biased into a neutral position, for example a central position, by means of spring elements engaging it from respective opposite sides. The apparatus includes at least four fixed photosensitive cells which are disposed symmetrically about the radiation source. Two of each of the photosensitive cells are connected to each of two circuits of an electrical transmission means which comprises two electrical circuits. The source of radiation is advantageously surrounded by a screen which is secured to the control stick for movement therewith. Preferably, two photosensitive cells are disposed at mutually opposed locations and connected in a common circuit with the cells disposed in one plane and the cells disposed in the opposite plane being mounted in opposition to each other.

United States Patent [191 Pocker et al.

[ 51 Apr. 29, 1975 1 DEVICE FOR PRODUCING ELECTRICAL SIGNALS BY MEANS OFA CONTROL STICK [75] Inventors: Erwin Pocker, Feldolling; GertGrundmann, Westerham. both of Germany [73] Assignee:Messerschmitt-Blokow-Blohm GmbH, Munich, Germany 22 Filed: Jan. 31, 197421 Appl. No.: 438,288

[30] Foreign Application Priority Data 3,190,131 6/1965 Daubcrt. Jr...250/231 R X 3.223.846 12/1965 Rochester 250/230 3,513,247 5/1970Anderson et al. 250/234 X 3,521,072 7/1970 Wipson ct al. 250/231 RPrimary Examiner walter Stolwein Attorney, Agent, or Firm-McGlew andTuttle [57] ABSTRACT A device for producing electrical signals,comprises a control stick which is pivotally mounted for back andforward movement intermediate its length. One end of the control stick,for example the bottom end, is provided with a source of luminousradiation adjacent this end, and the stick is biased into a neutralposition, for example a central position, by means of spring elementsengaging it from respective opposite sides. The apparatus includes atleast four fixed photosensitive cells which are disposed symmetricallyabout the radiation source. Two of each of the photosensitive cells areconnected to each of two circuits of an electrical transmission meanswhich comprises two electrical circuits. The source of radiation isadvantageously surrounded by a screen which is secured to the controlstick for movement therewith. Preferably, two photosensitive cells aredisposed at mutually opposed locations and connected in a common circuitwith the cells disposed in one plane and the cells disposed in theopposite plane being mounted in opposition to each other.

9 Claims, 5 Drawing Figures DEVICE FOR PRODUCING ELECTRICAL SIGNALS BYMEANS OF A CONTROL STICK BACKGROUND OF THE INVENTION 1. FIELD OF THEINVENTION This invention relates in general to the construction ofcontrol devices and, in particular, to a new and useful device forproducing electrical signals by means of a control stick.

2. DESCRIPTION OF THE PRIOR ART Control devices are known which includea pivotal control stick for effecting the transmission of controlsignals. With the known type of devices, the control signals produced byvarying the inclination of the control stick are used for controllingthe movement and position of hoisting units and machine tools or for theremote control of aircraft surfaces, for example. Control and steeringoperations of this kind require a sensitive actuation, if possible, witha complete elimination of inertial forces and an immediate response ofthe system to any change in the position of the control stick.

In a known remote control device for automatically moving bodies, atilting of the control stick provided results in the adjustment of twopotentiometers which are disposed in two control planes perpendicular toteach other. The control voltages, which are transformed into remotecontrol signals corresponding to the control planes, are a function ofthe control stick position and are tapped off of the potentiometers.

Such a device has several drawbacks. From the mechanical point of view,there must be provided a certain minimum size if a statisfactoryprecision is to be obtained. Limits are therefore set in respect tominiaturization of such a system. Further, potentiometers permit voltagevariations only in steps. They also have the disadvantage that apermanent use leads to abrasion and consequently corrosion of thesliders and turns, reducing the life of these parts and increasing thecontact resistances with the necessiity of frequent adjustment as areslt.

SUMMARY OF THE INVENTION The present invention provides an easilyoperable control stick unit of small size wherein voltages,approximately proportional to the angular position of the control stick,are delivered as control signals to a control device connected theretoand, during the operation, the mechanical wear of the parts ismaintained at a minimum. In accordance with the invention, this problemis solved by providing a source of luminous radiation mounted on one endof a pivotal control stick, and at least four fixed photosensitive cellswhich are disposed symmetrically about the source of radiation, with twoeach of said cells being connected in each one of two separateelectrical tranmission circuits.

In one embodiment of the invention, the source of radiation issurrounded by a screen which is secured to the control stick and thephotosensitive cells are disposed so that, in the neutral mid positionof the control stick, they extend parallel to the axis of the stick andtheir bottom edges are flush with the bottom edge of the screen.

In another embodiment of the invention, the screen is omitted and thephotosensitive cells are directly exposed to the source of radiation andlocated in planes forming an angle with the axis of the control stick inmid position.

The invention further provides a circuit arrangement for the electricalpart of the control stick unit in which two of the photosensitive cellsare opposed to two others, and each two are connected in a commoncircuit and mounted electrically in opposition to each other.

Theinvention has many advantages with respect to the prior art. In thefirst place, the simple construction of the control stick, whichrequires no intermediate mechanical parts for producing the variablecontrol voltages, permits a simple adaptation to the desired value ofthe controlvoltage. Thus, for special purposes, it is possible toprovide a miniaturization of the parts in a solid state constructionwhich has not been feasible with the known control stick unitsheretofore. Because the control stick is the single mobile part in thedevice and the source of radiation mounted thereon can be operated withundervoltage, the unit requires substantially no maintenance. Theactuation of the control stick 'is not hindered by any mechanicaltransmission member so that the ease of manipulation can be adjusted atany time to the desired degree by adjusting the springs retaining thestick in the neutral mid position. The photosensitive cells may beselected in accordance with the problem to be solved. At voltages ofabout 3 to 4 v and more, it is preferable to use photo-emissive cells.These cells are'connected into the circuit with the working voltageapplied thereto and are conductive only when irradiated. Theirconductivity attains a certain saturation at which the full appliedvoltage can pass through and may be collected.

It is also possible, however, to use photoconductive cells producing thevoltage themselves so that only the current for the source of radiationis to be supplied from a small battery. The desired voltage value mayalso be predetermined by choosing not only the type but also thequantity of the photocells disposed in each plane. Another advantage isthe fact that the voltage variation as a function of the stickinclination can be influenced by selecting an appropriate source ofradiation. For example, with a luminous source having the lamp bulbflattened on the front end, a more flattened voltage rise will. beobtained at small angles than at large angles of inclination of thestick, which is desired for some purposes. Possible variations in thebrightness of the luminous source can be made ineffective by adjustingthe saturation limit of the photosensitive cell to the smallestbrightness range. Thereby, a completely uniform collection of light and,consequently, delivery of voltage is obtained irrespective of thedirection in which the stick has been tilted.

Accordingly, it is an object of the invention to provide a device forproducing signals which includes a control stick which is pivotallymounted intermediate its length and which may be pivoted to effect thetransmission of control signals through a transmission means whichincludes two electrical circuits, the stick being biased into a neturalposition and being provided with a source of luminous radiation on anend which is spaced from the pivotal mounting thereof which issurrounded by at least four symmetrically arranged photosensitive cellsWith two of each of these cells being connected in respective ones ofthe two circuits.

A further object of the invention is to provide a device for producingsignals which is simple in design, rugged in construction and economicalto manufacture.

For an understanding of the principles of the invention, reference ismade to the following description of typical embodiments thereof asillustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

FIG. 1 is a transverse sectional view through a control deviceconstructed in accordance with the invention;

FIG. 2 is a view of the control device of FIG. 1 shown in an operativeposition;

FIG. 3 is a view similar to FIG. 1 of another embodiment of theinvention;

FIG. 4 is a circuit diagram for one tilting plane of the control stick;and

FIG. 5 is a view similar to FIG. 1 of another embodiment of theinvention.

GENERAL DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawingsin particular, the invention embodied therein in FIG. 1, comprises acontrol device, generally designated 50, which, for example, maycomprise a control mechanism for operating the surfaces of an aircraftand which includes a control stick 1 in the form of a double armed leverwhich is pivotally mounted in a pivot bearing or gimbal mounting 2 on atop wall of a container or frame 3. The bearing 2 is ad vantageously auniversal bearing and permits the control stick 1 to be tilted by anangle a in all of the planes which pass through the axis of the controlstick 1. The control stick is held in a neutral position, in this case acentral position, by four separate springs 4, which are connectedintermediate the length of a top arm portion la of lever l and frame 3at four locations which are spaced on frame 3 at 90 from each other.Springs 4 constitute biasing means for biasing stick 1 into a neturalposition.

In accordance with the invention, the control stick 1 also includesanother end portion or bottom end portion lb which carries a luminoussource 5 at a spaced location from the pivotal mounting 2, for example,at the bottom end. Luminous source 5 is supplied with electric currentby a connection extending through the stick, which has not been shown.At least four separate photosensitive cells 7a to 7d are arranged atequally spaced locations from the luminous source in a fixed positioninside of the frame 3 with their bottom edges flush with the bottom edgeof a screen 6 which is positioned around the lower end of controlstick 1. Photosensitive cell 7d, which is opposite to cell 70, shown inFIG. 2 is not indicated. In the embodiment shown, at least fourphotosensitive cells 7 are provided, but a number more than 4, forexample 8, 12 or even more, may be used for producing higher voltages.

The embodiment shown in FIG. 3 comprises a control device, generallydesignated 52, which includes a control stick or double armed lever 1',which is pivotally mounted on a universal joint 2 and is biased into aneutral position by springs 4, similar to the embodiment shown inFIG. 1. In the construction shown in FIG. 3, the luminous sourcecomprises a lamp 10, which is located on the arm portion lb of controlstick or double armed lever 1'. Lamp comprises a rounded glass bulbwhich irradiates the photosensitive cells 70', 7b, 7c and 7d, butwithout a screen interposed therebetween. Cells 7 are mounted so as tobe inclined with respect to the axis of the control stick in the neutralposition.

FIG. 4 shows a circuit diagram arrangement which includes a possibleseries connection of the photosensitive cells 7a and 7b which, forexample, may also be photo-emissive cells and thus connected in acircuit to which a working voltage is applied. Positive voltage isapplied to terminal 20 and a negative voltage is applied to terminal 21.Balancing resistances 22 and 23 are provided between the photo-emissivecells 7a and 7b, permitting a precise fixing or shifting of the startingpoint of the voltage increase. Between the balancing resistances 22 and23, a load resistance 24 is connected in parallel to the two cells 7aand 7b. The signal voltage for a control device (not shown) is collectedbetween terminals 25 and 26 which are located at the two ends of theload resistance 24. Outside of terminal 25, the circuit is closedthrough a ground terminal 27.

In the circuit arrangement shown in FIG. 4, the photosensitive cellsfunction in a passive manner, that is they are non-conducting as long asthey are not irradiated by a luminous source. Their conductivity riseslinearly with the incident luminous radiation up to a maximum value. Themaximum value of current flow should substantially correspond to theapplied voltage which can then be collected at the terminals 25 and 26.If active, that is photoconductive or photovoltaic cells are used,terminals 20 and 21 are connected to ground terminal 27. In such a case,the voltage is produced in the cells themselves, and can also becollected at terminals 25 and 26 up to a maximum value depending on thetype of end quantity of the cells used.

The control stick unit operates as follows:

In the vertical, that is, the neutral position of control stick 1,photosensitive cells 7 are not irradiated, as shown in FIG. 1, becauseof intervening screen 6. With the tilting of control stick 1 by an anglea, photosensitive cell 7a is irradiated by the light in a degreedetermined as a function of the angle, and it becomes correspondinglyconductive for the current flowing from terminal 20 until it is in thelimit position of the stick, as shown in FIG. 2. The full appliedpositive voltage can be collected between terminals 25 and 26.

While tilting control stick 1 by an angle a in the opposite direction,negative current flows from terminal 21 through photosensitive cell 7band can be collected between terminals 25 and 26 as a negative voltage.The same is obtained with photosensitive cells 7c and 7d if controlstick 1 is tilted perpendicularly to the drawing plane and a positive ornegative voltage can be collected in the respective circuit, which isarranged in the same manner as shown in FIG. 4.

Control stick 1, mounted in a ball-socket swivelbearing, can be tiltedin any direction, and the voltage produced corresponds to the angularposition and directional orientation of the stick. In the example ofFIG. 3, in the neutral position of control stick 1', the currentsflowing through the two branches of the circuit and resulting from theirradiation of the photosensitive cells, compensate each other. At thetilting of stick 1', a difference voltage is obtained corresponding tothe angular position and orientation and resulting from the voltagesproduced in the respective photosensitive cells 7a to 7d. In the samemanner as described v in connection with FIGS. 1 and 2, this differencevoltage can be collected at terminals 25 and 26. The embodiment of FIG.3 has the advantage of better utilizing the radiation.

It is evident that instead of being a two-armed lever, as provided inthe examples shown, the control stick I, 1 may also be designed as aone-armed lever, such as the control stick 3 shown in FIG. 5.

The control stick 3 is universally mounted on a universal mounting 2" asshown in FIG. 5, and it includes a luminous source 5", which is locatednear its bottom end at a spaced location from pivot 2". Photoelectriccells 7a", 7b", 7c" and 7d"are arranged symmetrically around luminoussource 5", as in the other embodiments.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

l. A device for producing signals, comprising a control stick having amanipulatable handle portion and being universally pivotally movable totransmit control signals, universal mounting means mounting said controlstick for universal pivotal movement, biasing means urging said controlstick into a neutral position, transmission means comprising twoelectrical circuits adapted to be influenced by the angular position ofsaid control stick, a source of luminous radiation mounted on andadjacent an end of said control stick at a spaced location from itspivotal mounting, means associated with said luminous radiation sourceto shield the photocells from the source in predetermined positions ofsaid control stick, and at least four fixed photosensitive cellsarranged in opposed pairs disposed symmetrically about said radiationsource and two being connected in each of said two circuits, the centerlines of said cells each being in a plane containing the axis of saidcontrol stick in said neutral position and being disposed at an angle toeach other which is less than 180.

2. A device for producing signals, according to claim 1, wherein saidshielding means comprises a screen surrounding said source of radiationand carried by said control stick and in which said photosensitive cellshave bottom edges which extend in the same plane as the bottom edge ofsaid screen.

3. A device for producing signals, according to claim 1, wherein saidphotosensitive cells are directly exposed to the said source ofradiation.

4. A device for producing signals, according to claim 1, wherein saidelectrical circuits include a circuit having two photosensitive cellsdisposed at mutually opposed locations and being disposed in a planewhich is perpendicular to the plane of the other two of said cells.

5. A device for producing signals, according to claim 1, wherein saidphotosensitive cells are passive cells.

6. A device for producing signals, according to claim 1, wherein saidphotosensitive cells are active cells.

7. A device for producing signals, according to claim 1, wherein saidcontrol stick is a double-armed lever, including an upper portion whichis adapted to be engaged by a persons hand and a lower portion on theopposite side of said pivotal mounting carrying said source of luminousradiation.

8. A device for producing signals, according to claim 7, wherein saidsource of luminous radiation is carried on the outer end of the bottomof said control stick.

9. A device for producing signals, according to claim 1, wherein saidcontrol stick comprises a single arm lever, said luminous source ofradiation being spaced from said pivotal connection upwardly along saidcon-

1. A device for producing signals, comprising a control stick having amanipulatable handle portion and being universally pivotally movable totransmit control signals, universal mounting means mounting said controlstick for universal pivotal movement, biasing means urging said controlstick into a neutral position, transmission means comprising twoelectrical circuits adapted to be influenced by the angular position ofsaid control stick, a source of luminous radiation mounted on andadjacent an end of said control stick at a spaced location from itspivotal mounting, means associated with said luminous radiation sourceto shield the photocells from the source in predetermined positions ofsaid control stick, and at least four fixed photosensitive cellsarranged in opposed pairs disposed symmetrically about said radiationsource and two being connected in each of said two circuits, the centerlines of said cells each being in a plane containing the axis of saidcontrol stick in said neutral position and being disposed at an angle toeach other which is less than 180*.
 2. A device for producing signals,according to claim 1, wherein said shielding means comprises a screensurrounding said source of radiation and carried by said control stickand in which said photosensitive cells have bottom edges which extend inthe same plane as the bottom edge of said screen.
 3. A device forproducing signals, according to claim 1, wherein said photosensitivecells are directly exposed to the said source of radiation.
 4. A devicefor producing signals, according to claim 1, wherein said electricalcircuits include a circuit having two photosensitive cells disposed atmutually opposed locations and being disposed in a plane which isperpendicular to the plane of the other two of said cells.
 5. A devicefor producing signals, according to claim 1, wherein said photosensitivecells are passive cells.
 6. A device for producing signals, according toclaim 1, wherein said photosensitive cells are active cells.
 7. A devicefor producing signals, according to claim 1, wherein said control stickis a double-armed lever, including an upper portion which is adapted tobe engaged by a person''s hand and a lower portion on the opposite sideof said pivotal mounting carrying said source of luminous radiation. 8.A device for producing signals, according to claim 7, wherein saidsource of luminous radiation is carried on the outer end of the bottomof said control stick.
 9. A device for producing signals, according toclaim 1, wherein said control stick comprises a single arm lever, saidluminous source of radiation being spaced from said pivotal connectionupwardly along said control stick.